1. Field of the Invention
The present invention relates to cups used for drinking, and more particularly to cups which have a lid associated therewith. Still more particularly, the present invention is related to a cup having an automatic seal feature associated with the lid which automatically seals the cup whenever the cup is not subjected to pressure applied thereto by the user.
2. Description of the Related Art
Cups are used widely for drinking liquid. Common cups have an open mouth at which a person may sip or place a straw into the cup to suckingly withdraw liquid. Problematically, an open mouth unrestrictedly permits the fluid contained in the cup to exit the cup in the event the cup is upset in some untoward manner. Thus, liquid within the cup can spill therefrom in the event the cup is dropped or dislodged from, or tipped in relation to, a resting surface, or if the cup is subjected to oscillations which generate liquid sloshing over the rim of the mouth of the cup, such as may happen when the cup is placed upon the dashboard of a moving motor vehicle.
To at least partly overcome the ease by which liquid contained in the cup may undesirably exit the cup, some cups are provided with a cap which snaps onto the rim of the cup. These types of cups are commonly found at fast food outlets for coffee, pop and other beverages. The cap has one or more discrete openings that allow a user access to the liquid only thereat. In theory, by limiting the openings of the cap, the liquid is more definitely confined to remain within the cup during such events as the liquid sloshing produced by motor vehicle movements. In practice, however, if the cup tips off the dashboard, the liquid will exit the openings in the cap as the cup crashes upon the floor, and, perhaps, the cap will pop off, thereby emptying the liquid contents of the cup even faster.
Some "sports" cups have caps that are better secured, such as by a threading engagement therebetween, and have an aperture therein through which a straw snugly passes. The straw usually has a user removable cap. Some of these cups have a manually operated pop-up vent which is sealed when pushed down and open when pushed up. These cups, while improved, still suffer from the fact that they will empty their liquid contents in the event the cup is tipped sideways, unless, fortuitously, the straw had been previously manually capped, the vent had been previously manually pushed closed, and the fit between the aperture in the lid and the straw was truly sealing.
Accordingly, what is needed is a cup which provides automatic control over sealing of the liquid within the cup.